1. Field of the Invention
The present invention relates to orthopedic bracing, and more specifically to apparatus and methods for decelerating an orthosis to prevent hyperextension and/or hyperflexion.
2. Description of the Related Art
Many orthopedic braces are configured to be secured to an extremity of a wearer to control the motion of a joint. For example, one common category of braces is configured to be secured to the wearer's leg in order to support the knee. Such braces may be used in a post-operative setting, or to prevent injury to a healthy knee, for example. Many of these knee braces include one or more mechanisms that control the range of motion of the knee and prevent the wearer from hyperextending and/or hyperflexing the knee.
A mechanical stop is one common mechanism for controlling the range of knee motion. Such a stop is positioned within the hinge and in the plane of rotation of the hinge arm(s) to thereby interfere with the hinge motion at one or more prescribed angular settings. When the hinge arm(s) reaches the prescribed angular setting, it (they) contacts the stop and the stop prevents the hinge arm(s) from rotating any farther. The hinge may include an extension stop to limit the range of motion as the knee is extended, or a flexion stop to limit the range of motion as the knee is flexed. The hinge may also include both an extension stop and a flexion stop.
Mechanical stops are generally constructed of hard materials, because they must be capable of withstanding high stresses. For example, metals like steel, zinc, or aluminum are frequently used. Similar materials are also generally used to construct the hinge arms, which must also be capable of withstanding high stresses. Unfortunately, as a metal hinge arm contacts a metal stop, an audible clicking sound is often made. This noise can be an annoyance to brace wearers. Further, as metal contacts metal, motion of the brace comes to an abrupt halt, which can be jarring and uncomfortable for brace wearers.
Some mechanical stops are constructed of relatively soft and flexible materials. Soft stops can reduce noise within a brace and increase wearer comfort by dampening the impact between a hinge arm and the stop. However, the qualities of soft stops that make them attractive for reducing noise and increasing wearer comfort also make them less attractive for achieving other objectives. For example, soft stops are generally not durable enough to withstand the high stresses that can be applied to mechanical stops. Further, the flexibility of a soft stop reduces the capability of the stop to provide precise motion control. If it is desired to prevent a knee brace wearer from flexing his or her knee past a certain angle, a soft stop may disadvantageously flex too much, thus allowing the wearer's knee to flex past the desired angle.